Optical Signal Processing Research Papers (original) (raw)

Two anamorphic and achromatic Fourier processors were designed and constructed using diffractive and refractive cylindrical lenses. The diffractive lenses are holographic lenses recorded on silver halide material. In both processors the achromatic one-dimensional Fourier transform plane was obtained with two holographic lenses and one refractive cylindrical lens. The image with the same magnification in both directions at the output plane was formed with two different combinations of lenses. The differences between the two processors are analyzed, and in both cases the chromatic aberration in the Fourier plane and in the output plane is evaluated. Even though single cylindrical refractive lenses were used to image in one direction, good results were obtained.

- by Jesús Atencia
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- Mechanical Engineering, Optical Signal Processing, Applied Optics, Optical physics

The coherent time-stretch transform enables high-throughput acquisition of complex optical fields in single-shot measurements. Full-field spectra are recovered via temporal interferometry on waveforms dispersed in the temporal near... more

We present a detailed description and a first theoretical study of an improved concept for high frequency self-pulsations (SP) in multi-section (MS)-DFB-lasers with an integrated phase tuning section. The DFB-wavelengths of the two DFB sections are spectrally detuned by nearly the stopband width using two gratings with different grating periods. If both DFBsections are operated at lasing conditions and an appropriate phase is chosen, we obtain beating-type SP with a frequency given by the spectral distance of two lasing modes. Good agreement between theory and experiment is obtained with respect to the role of the detuning, the role of the phase section, as well as the synchronization to external injected signals. The modeling shows a strong nonlinear coupling of the two involved modes via the carrier densities. This effect is important for the mutual coherence and for the observed locking of the beating oscillations to external signals. From the results of the calculations we draw the conclusion that even higher SP frequencies can be obtained based on the new concept.

- by Olaf Brox
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- Quantum Physics, High Frequency, Organic Semiconductor Laser, Oscillations

This paper presents recent results in the development of novel ultrafast technologies based on the generation and application of stabilized optical frequency combs. By using novel active resonant cavity injection locking techniques, filtering, modulation and detection can be performed directly on individual components of the frequency comb enabling new approaches to optical waveform synthesis, waveform detection and matched filtering, with effective signal processing bandwidths in excess of 1 THz.

- by Peter Delfyett
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- Quantum Physics, Signal Processing, Ultrafast Optics, Matched Filter

Clock recovery is a fundamental operation in digital telecommunications systems, where the receiver synchronizes itself to the transmitter timing. In optical clock recovery, this operation is made using optical signal processing methods. This paper reviews the physical principles and classifies the various optical clock recovery methods developed during the last 20 years.

- by Tuomo von Lerber
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- Optical Signal Processing, Optical physics, High Speed, Optical Fiber Technology

Optical packet switching promises to bring the flexibility and cfficiency of the Internet t o transparcnt optical networking with bit rates extending beyond that currently available with electronic router technologies. New optical signal processing techniques have been demonstrated that enable routing at bit rates from 10 Gbis to beyond 40 Ghis. In this article we review these signal processing techniques and how all-optical wavelength converter technology can he used to implement packet switching functions. Specific approaches that utilize ultra-fast all-optical nonlinear fiber wavelength converters and monolithically integrated optical wavelength converters are discussed and research results prcsented.

- by Suresh Rangarajan and +1
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- Distributed Computing, Signal Processing, Nonlinear Optics, Routing

This paper presents an approach to designing narrowband digital filters that are realizable using optical allpass building blocks. We describe a top-down design method by explicitly examining the derivation of an Infinite Impulse Response (IIR) architecture. Our result demonstrates a design that can achieve a 0.0025π passband edge while providing 60dB stopband attenuation. The design is aimed to reduce filter pole magnitudes, providing tolerance for waveguide losses and fabrication errors. The narrowband filter is based on the foundation of latticed allpass sections, which makes it naturally realizable using basic photonic components. Furthermore, analysis is performed on delay length variations that can result from the fabrication process.

- by truong nguyen
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- Mathematics, Computer Science, Photonics, Adaptive Optics

L'estesa rete di torri costruite tra XII e XIV secolo nella Campagna Romana ci spinge a ritenere che questo tipo di edifici possa non aver avuto mera funzione difensiva. Omogenea distribuzione delle torri sul territorio e loro non casuale disposizione - come dimostra il caso studio del Parco dell'Appia Antica (450 ettari circa) erano pensate per scorgersi a vicenda - consentono di ipotizzare che, sia pure accettando una pluralità di funzioni magari sin dall'origine, la scelta sia stata quella di monumenti di di segnalazione

The intensive investment in optical microelectromechanical systems (MEMS) in the last decade has led to many successful components that satisfy the requirements of lightwave communication networks. In this paper, we review the current state of the art of MEMS devices and subsystems for lightwave communication applications. Depending on the design, these components can either be broadband (wavelength independent) or wavelength selective. Broadband devices include optical switches, crossconnects, optical attenuators, and data modulators, while wavelength-selective components encompass wavelength add/drop multiplexers, wavelength-selective switches and crossconnects, spectral equalizers, dispersion compensators, spectrometers, and tunable lasers. Integration of MEMS and planar lightwave circuits, microresonators, and photonic crystals could lead to further reduction in size and cost.

- by Yougui Wu and +1
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- Optical Switch, Photonic Crystal, Mechanical systems, Optical Signal Processing

Optical signal processing techniques employ a wide range of devices and various nonlinearities to achieve multiple network functionalities. The choice of nonlinearity can also impact the relative efficiency, both in terms of energy and material consumption, of the signal processing function being implemented. Techniques for some of the important functionalities, wavelength multicasting, wavelength-division multiplexing to time-division multiplexing, add-drop multiplexing, and wavelength exchange are compared in terms of the used optical spectrum, number of pumps required, and optical energy consumed. These include varieties of four-wave mixing, cross-phase modulation, Kerr-effectbased polarization rotation in optical fibers, and three-wave mixing in lithium niobate waveguides (WGs). Future possibilities of greener optical signal processing using on-chip WG technologies are discussed within the scope of recent developments in the dispersion tailored, highly nonlinear WGs.

- by Scott Nuccio
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- Quantum Physics, Nonlinear Optics, Optical Waveguides, Optical Waveguide

Ultrahigh nonlinear tapered fiber and planar rib Chalcogenide waveguides have been developed to enable highspeed all-optical signal processing in compact, low-loss optical devices through the use of four-wave mixing (FWM) and cross-phase modulation (XPM) via the ultra fast Kerr effect. Tapering a commercial As 2 Se 3 fiber is shown to reduce its effective core area and enhance the Kerr nonlinearity thereby enabling XPM wavelength conversion of a 40 Gb/s signal in a shorter 16-cm length device that allows a broader wavelength tuning range due to its smaller net chromatic dispersion. Progress toward photonic chip-scale devices is shown by fabricating As 2 S 3 planar rib waveguides exhibiting nonlinearity up to 2080 W −1 · km −1 and losses as low as 0.05 dB/cm. The material's high refractive index, ensuring more robust confinement of the optical mode, permits a more compact serpentine-shaped rib waveguide of 22.5 cm length on a 7-cmsize chip, which is successfully applied to broadband wavelength conversion of 40-80 Gb/s signals by XPM. A shorter 5-cm length planar waveguide proves most effective for all-optical time-division demultiplexing of a 160 Gb/s signal by FWM and analysis shows its length is near optimum for maximizing FWM in consideration of its dispersion and loss.

- by Barry Luther-davies
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- Quantum Physics, Nonlinear Optics, Optical Waveguide, Refractive Index

Compact optical channel dropping filters incorporating side-coupled ring resonators as small as 3 m in radius are realized in silicon technology. Quality factors up to 250, and a free-spectral range (FSR) as large as 24 nm are measured. Such structures can be used as fundamental building blocks in more sophisticated optical signal processing devices.

- by Sai Chu
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- Optical Waveguides, Quality Factor, Q factor, Optical Signal Processing

Micro/nanostructure photonic devices offer a variety of enabling properties, including low power-consumption, cost-efficient, compact size, and reliability. These distinctive features have been exploited in a wealth of applications ranging from telecommunication and optical interconnect to photonic network on chip. In this paper, we review two main classes of micro/nanostructure photonic devices, to provide the kinds of functions for optical signal processing.

- by Xiaomeng Sun
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- Optical Signal Processing, Low Power Consumption, Cost Efficiency, Optical fiber

Focusing and guiding light into semiconductor nano-structures can deliver revolutionary concepts for photonic devices, which offer a practical pathway towards next-generation power-efficient optical networks. In this review, we consider the prospects for photonic switches using semiconductor quantum dots (QDs) and photonic cavities which possess unique properties based on their low dimensionality. The optical nonlinearity of such photonic switches is theoretically analysed by introducing the concept of a field enhancement factor. This approach reveals a drastic improvement in both power-density and speed, which is able to overcome the limitations that have beset conventional photonic switches for decades. In addition, the overall power consumption is reduced due to the atom-like nature of QDs, as well as the nano-scale footprint of photonic cavities. Based on this theoretical perspective, the current state-of-the-art QD/cavity switches are reviewed in terms of various optical nonlinearity phenomena that have been utilized to demonstrate photonic switching. Emerging techniques, enabled by cavity nonlinear effects such as wavelength tuning, Purcell-factor tuning and plasmonic effects, are also discussed.

- by Chao-Yuan Jin
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- Nanophotonics, Plasmonics, Optical switching, Quantum Dots

We report the first demonstration of high bit rate signal processing by a fiber-based photonic wire. We achieve 160 Gb/s demultiplexing via four wave mixing in a 1.9 microm diameter photonic wire tapered from As(2)S(3) chalcogenide glass single mode fibre, with very low pump power requirements ( < 20 mW average power, 0.45 W peak power), enabled by a very high nonlinearity (gamma approximately 7850 W(-1) km (-1) ) and greatly reduced dispersion.

- by Ishwar Aggarwal
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- Optics, Telecommunications, Optical Signal Processing, Optical physics

With the current technology revolution, underwater wireless sensor networks (UWSNs) find several applications such as disaster prevention, water quality monitoring, military surveillance and fish farming. Nevertheless, this kind of networks faces a number of challenges induced by the nature of the underwater environment and its influence on the network physical media. Therefore, the ultimate objective of this paper is to lay down the key aspects of the physical layer of the underwater sensor networks (UWSNs). It discusses issues related to the characteristics and challenges of the underwater communication channel, differences between terrestrial wireless sensor networks and UWSNs, and acoustic propagation models in underwater. The paper also surveys some of the underwater acoustic modems. This study is essential to better understand the challenges of designing UWSNs and alleviate their effects.

In densely populated cities or indoor environments, limited accessibility to satellites and severe multipath effects significantly decrease the accuracy and reliability of satellite-based positioning systems. To meet the needs of "seamless navigation" in these challenging environments, an advanced terrestrial positioning system is under development. A new principle of mobile robot navigation capable of working in a complex unknown landscape (another planet or just on a cross-country terrain) is proposed. The optoelectrical method proposed has a good spatial domain resolution and immunity to multipath, as well as new optical means for "technical vision" realization. Two related problems are solved: creation of a technical vision system for recognition of images of an unfamiliar landscape and determination of the direction to the initial point of the movement trajectory of the mobile transport robot. Issues of principle design and also of functioning and interaction of system units and elements are described. A mathematical apparatus for processing digital information inside the system and for determining the distances and angle measurements in the system proposed is developed. Some important parameters are analytically determined: expected accuracy, functioning speed, range of action, power issues, etc.

We report the first experimental demonstration of simultaneous multi-impairment monitoring of phase-modulated 40 Gbit/s nonreturn to zero differential phase-shift keying (NRZ-DPSK) and 640 Gbit/s return-to-zero (RZ)-DPSK optical signals. Our approach exploits the femtosecond response time of the Kerr nonlinearity in a centimeter-scale, highly nonlinear, dispersion engineered chalcogenide planar waveguide to perform THz bandwidth RF spectrum analysis. The features observed on the radio-frequency (RF) spectrum are directly utilized to perform simultaneous group velocity dispersion and in-band optical signal-to-noise ratio (SNR) monitoring. We also numerically investigate the measurement accuracy of this monitoring technique, highlighting the advantages, and suitability of the chalcogenide rib waveguide.

Recent measurements of photon tunneling through individual subwavelength pinholes in a gold film covered with a layer of polydiacetylene (Phys. Rev. Letters 88, 187402 (2002)) provided strong indication of "photon blockade" effect similar to Coulomb blockade phenomenon observed in single-electron tunneling experiments. Here we report first observation of photon tunneling been blocked (gated) by light at a different wavelength. This observation suggests possibility of building new class of photon tunneling gating devices for all-optical signal processing.

- by Igor Smolyaninov
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- Engineering, Quantum Optics, Signal Processing, Nonlinear Optics

In this paper, an 11.3 Gbps CMOS SONET compliant transceiver designed to work in both RZ and NRZ data formats is presented. Using a configurable high-speed transmit path utilizing an AND gate and a duty cycle adjustment circuit, the transmitter can switch output format between RZ and NRZ. The TX driver exhibits 17 ps rise/fall times, 0.25 ps rms RJ, and 2 ps pp DJ. In RZ mode, TX output duty cycle can be adjusted within 40-60% range. To improve input sensitivity in both RZ and NRZ reception, the receiver incorporates a limiting amplifier with a distributed threshold adjustment circuit. It achieves 5 mVpp-diff RX input sensitivity with 0.54 UI high-frequency jitter tolerance. An adaptation scheme based on nested linear search is implemented to control the distributed threshold adjustment circuit. While demonstrating the integration of RZ/NRZ functionality into a single-chip solution using 65 nm CMOS technology, the transceiver core occupies 1.36 mm 2 and consumes 214 mW.

- by Ullas Singh and +1
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- Optical Communication, Optical Signal Processing, Logic Gate, Electrical And Electronic Engineering

All-optical digital devices are key components for advanced signal processing in next generation optical networks and optical computing. In most digital systems, photonic integrated circuits are required to carry out high-speed energy efficient functionalities. In this paper, an entire set of integrable all-optical clocked flip-flops and an all-optical binary counter are proposed, as applications of SR latches and logic gates previously introduced in literature. The SR latch is based on gain quenching mechanism between two coupled ring lasers using a semiconductor optical amplifier (SOA) as active element. Photonic logic functions are carried out by exploiting four wave mixing (FWM) and cross gain modulation (XGM) nonlinear effects in SOAs. Different flip-flop logical functionalities, including SR-, D-, T-, and JK-types, as well as an all-optical binary counter, are obtained by adding one of the logic gates, or a combination of them, to the latch scheme. The effectiveness of the proposed schemes is demonstrated by extinction ratio and Q-factor measurements. All solutions are tunable in the whole C-band and can work at different counting rate without any reconfiguration. Photonic integration allows to increase the functioning rate beyond gigahertz and reduce the switching energy. Index Terms-Optical flip-flop, optical logic gates, optical signal processing, semiconductor optical amplifier (SOA). I. INTRODUCTION I N ORDER to meet the ever-increasing demand of data communication for future optical networks, high-speed digital processing is required.

- by gianluca berrettini
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- Quantum Physics, Signal Processing, Q factor, Optical computing
- by Yujia Wang
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- Photonics, Adaptive Optics, Optical Waveguides, Design process

During the past years, monolithic integration in InP has been the driving force for the realization of integrated photonic routing systems. The advent of silicon as a basis for costeffective integration and its potential blend with III-V material is now opening exciting opportunities for the development of new, high-performance switching and routing equipment. Following this rationale, BOOM-as a European research initiative-aims to develop compact, cost-effective, and power-efficient silicon photonic components to enable optical Tb/s routers for current and new generation broadband core networks. This "siliconization" of photonic routers is expected to enable ultrahigh bit rates as well as higher levels of integration and power efficiency. The BOOM "device portfolio" includes all-optical wavelength converters, ultradense wavedivision multiplexing (UDWDM) photodetectors, and high-speed transmitters; all based on silicon waveguide substrates. Here, we present the device concepts, the fabrication of photonic building blocks and the experiments carried out as the initial steps toward the realization of the first high-capacity silicon photonic router.

We show that the Fresnel field at a fraction of the Talbot distance behind a complex transmittance grating is conveniently described by a matrix operator. We devote special attention to a discrete-type grating, whose basic cell (of length d) is formed with a finite number (Q) of intervals of length d/Q, each with a constant complex transmittance. Ignoring the physical units of the optical field, we note that the transmittance of the discrete grating and its Fresnel field belong to a common Q-dimensional complex linear space (V Q ). In this context the Fresnel transform is recognized as a linear operator that is represented by a Q ϫ Q matrix. Several properties of this matrix operator are derived here and employed in a discussion of different issues related to the fractional Talbot effect. First, we review in a simple manner the field symmetries in the Talbot cell. Second, we discuss novel Talbot array illuminators. Third, we recognize the eigenvectors of the matrix operator as discrete gratings that exhibit self-images at fractions of the Talbot distance. And fourth, we present a novel representation of the Fresnel field in terms of the eigenvectors of the matrix operator.

- by Juan Ibarra
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- Optical computing, Optical Signal Processing, Diffractive optics

9th International Conference on Signal and Image Processing (SIGL 2022) is a forum for presenting new advances and research results in the fields of Digital Image Processing. The conference will bring together leading researchers, engineers and scientists in the domain of interest from around the world. The scope of the conference covers all theoretical and practical aspects of the Signal, Image Processing & Pattern Recognition.

In any country, warning text is described on the signboards or wall papers to follow by everybody. This paper present Myanmar character recognition from various warning text signboards using block based pixel count and eight-directions chain code. Character recognition is the process of converting a printed or typewritten or handwritten text image file into editable and searchable text file. In this system, the characters on the warning signboard images are recognized using the hybrid eight direction chain code features and 16-blocks based pixel count features. Basically, there are three steps of character recognition such as character segmentation, feature extraction and classification. In segmentation step, horizontal cropping method is used for line segmentation, vertically cropping method and bounding box is used for connected component character segmentation. In the classification step, the performance accuracy is measured by two ways such as KNN (K's Nearest Neivour) classifier and feature based approach of template matching on 150 warning text signboard images.

- by IJRE ORG
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- Character Recognition, Myanmar, Optical Signal Processing

In recent years, reversible logic has emerged as a promising computing paradigm having application in low-power CMOS, quantum computing, nanotechnology and optical computing. Optical logic gates have the potential to work at macroscopic (light pulses carry information), or quantum (single photons carry information) levels with great efficiency. However, relatively little has been published on designing reversible logic circuits in all-optical domain. In this paper, we propose and design a novel scheme of Toffoli and Feynman gates in all-optical domain. We have described their principle of operations and used a theoretical model to assist this task, finally confirming through numerical simulations. Semiconductor optical amplifier (SOA)-based Mach–Zehnder interferometer (MZI) can play a significant role in this field of ultra-fast all-optical signal processing. The all-optical reversible circuits presented in this paper will be useful to perform different arithmetic (full adder, BCD adder) and logical (realization of Boolean function) operations in the domain of reversible logic-based information processing.

This paper reviews the work performed under the European ESPRIT project DO_ALL (Digital OpticAL Logic modules) spanning from advanced devices (semiconductor optical amplifiers) to all-optical modules (laser sources and gates) and from optical signal processing subsystems (packet clock recovery, optical write/store memory, and linear feedback shift register) to their integration in the application level for the demonstration of nontrivial logic functionality (all-optical bit-error-rate tester and a 2 2 exchange-bypass switch). The successful accomplishment of the project's goals has opened the road for the implementation of more complex ultra-high-speed all-optical signal processing circuits that are key elements for the realization of all-optical packet switching networks.

We propose and demonstrate a novel fiber-based all-optical regenerator, where the wavelength shift induced by cross-phase modulation is employed for level discrimination. Regeneration of a 10-Gb/s signal using the proposed scheme improves the -factor by 1.8 dB. The scheme is stable and robust against changes in environmental conditions. Index Terms-Optical fiber communication, optical Kerr effect, optical repeaters, optical signal processing.

In this letter, we demonstrate a new design for a XOR optical gate operating in the GHz regime using the cross-polarization modulation effect in a semiconductor optical amplifier. Dynamic and optically controlled polarization rotation in the devices is used to control the output power of the device. Static extinction ratio of the order of 20 dB can be obtained. Bit rate doubling at rate of 1.2 and 2.5 Gb/s have been demonstrated.

All-optical exclusive-OR (XOR) logic gate is a basic and crucial element for optical signal processing. We propose and demonstrate a novel high-speed all-optical XOR gate based on fourwave mixing (FWM) in a semiconductor optical amplifier, with optical return-to-zero differential phase-shift keying (RZ-DPSK) input signals. With this constant-envelope modulation format, the patterning effect-induced signal degradation in semiconductor optical amplifier (SOA) is alleviated. The proposed XOR gate can accommodate both two-input and three-input logic operations, which offer better flexibility for cascaded all-optical processing. Experimental demonstrations at 10-and 20-Gb/s verified the logic integrity of the proposed XOR gate. In addition, the XOR output tolerance against temporal misalignment among the data inputs is also experimentally investigated.

The purpose of this paper is twofold. First, a simple but comprehensive and powerful arrayed-waveguide grating (AWG) field model is presented which, based on Fourier optics, borrows some principles of that developed by Takeouchi and coworkers [1] for the analysis of reflective-type AWGs for optical signal processing, but at the same time adds more features, such as the calculation of device losses and the refinement of the mathematical model to obtain a simple expression for the output field for any input-output waveguide configuration where the meaning of the different high-level parameters of the AWG becomes very clear to the reader. Second, we elaborate on the model developed to present an useful design procedure of the AWG based on two steps illustrated by design flowcharts.

- by Pascual Muñoz
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- Optics, Medical Imaging, Signal Processing, Fiber Optics

The authors demonstrate a novel all-optical T-flip-flop (TFF) layout utilizing a single optical latching element that comprises an integrated semiconductor optical amplifier and Mach-Zehnder inteferometer and a feedback loop. Experimental proof-of-concept verification is presented at 8 Mb/s using off-the-shelf bulk components and a fiber-based feedback implementation. The proposed TFF architecture requires the minimum number of active components and just a single toggling signal as input. Its simple circuit design is amenable with photonic integration and holds the credentials for operation at multi-Gb/s speeds.

- by T. Alexoudi and +1
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- Optical Switch, SEMICONDUCTOR OPTICAL AMPLIFIER, Optical Signal Processing, Optical physics

Synchronisation is an important and critical issue in high-speed all optical time division multiplexed (OTDM) packet routing and transmission. In this paper we present a technique for separating the clock synchronization pulse from an incoming optical time division multiplexed data packet, based on all-optical switching devices with optical feedback. A 1X2 OTDM router composed of three Symmetric Mach-Zehnders (SMZs) is proposed. Simulation results show that synchronization between clock and data packet is achievable and the packet payload can be successfully switched to the correct destination port.

Integrated components, including microdisk lasers, photodetectors, and wavelength selective circuits, for optical network-on-chip and all-optical signal processing are presented using a complementary metal-oxide-semiconductor compatible... more

Chalcogenide glasses, which contain S, Se or Te atoms combined with network forming elements such as Ge, As, Sb have the largest third order optical nonlinearity of any inorganic glass. As a result they are attractive candidates for fibre and waveguide devices for all-optical signal processing in the telecommunications bands. In this talk I will review our recent progress in alloptical devices such as regenerators, wavelength converters and other devices in chalcogenide glasses.

- by Andrei Rode
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- Optical Signal Processing, Chalcogenide Glass

We demonstrate integrated all-optical 2R regenerators based on Kerr optical nonlinearities (subpicosecond response) in chalcogenide glass waveguides with integrated Bragg grating filters. By combining a low loss As 2 S 3 rib waveguide with an inwaveguide photo-written Bragg grating filter, we realize an integrated all-optical 2R signal regenerator with the potential to process bit rates in excess of 1 Tb/s. The device operates using a combination of self phase modulation induced spectral broadening followed by a linear filter offset from the input center wavelength. A nonlinear power transfer curve is demonstrated using 1.4 ps pulses, sufficient for suppressing noise in an amplified transmission link. We investigate the role of dispersion on the device transfer characteristics, and discuss future avenues to realizing a device capable of operation at subwatt peak power levels.

- by Martin Rochette
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- Quantum Physics, Nonlinear Optics, Integrated Optics, IEEE

The parametric characterization of a nonreturnto-zero (NRZ) to return-to-zero (RZ) data format converter based on the external optical NRZ injection of a TO-46-can packaged vertical-cavity surface-emitting laser (VCSEL) directly modulated by a 10 GHz electrical pulse is demonstrated. The electrical-pulse modulation induced gain switching of the VCSEL is initiated under external optical NRZ data injection that increases the relaxation oscillation frequency of the homemade VCSEL from 2.2 to 7.4 GHz, thereby enabling its electrical modulation bandwidth up to 10 GHz. The external NRZ injection reduces the lasing threshold and enlarges the modulation depth of the VCSEL so that the converted RZ data pulsewidth can be shortened to 27 ps with a slightly increased peak-to-peak negative frequency chirp of 4.3 GHz (corresponding to a chirp parameter of 122 MHz/ps). The chirp and bit error rate (BER) display strong correlations with the injection power and the biased current of the VCSEL. With external injection, the receiving power required for achieving a BER below 10 9 at 10 Gbit/s is 19 5 dBm, and a power penalty of 16 dB is observed when the dc bias of the electrical-pulse modulated VCSEL is decreased by only 10% from the threshold condition.

We review waveform analysis and optical performance monitoring of ultrabroadband signals using a photonicchip-based radio-frequency spectrum analyzer. This approach offers the potential for fast integrated monitoring and characterization... more

- by Barry Luther-davies
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- Quantum Physics, Nonlinear Optics, Ultrafast Optics, Optical Waveguide

The use of discrete but interconnected SOA -MZI switches for performing logical and highly functional processing tasks, demonstrating the multi-functional potential of the photonic switching elements is discussed. An all-optical 3R burst-mode receiver consisting of four SOA -MZI switches and operating error-free with 40 Gb/s optical bursts, proving that interconnection of multiple switching units can lead to the realisation of key network node functionalities offering increased intelligence at the physical layer is presented. In order to allow for easier interconnectivity between the SOA -MZI switches and to provide compactness and cost effectiveness to the developed subsystems, the integration of multiple switches into the same platform is proposed. To this end, the implementation of the first integrated quadruple SOA -MZI switch array is reported, increasing the integration density level and reducing packaging and pigtailing costs. Finally, possible applications of integrated multiple switch arrays are discussed, indicating their suitability for producing compact circuits performing common processing tasks in a multiwavelength environment, as well as their potential to lead to the development of an all-optical highspeed packet switched node by implementing critical packet switching functionalities in a compact and efficient way.